Efficient production of l-lactic acid with high optical purity by alkaliphilic Bacillus sp. WL-S20

Highly efficient polymer-grade l-lactic acid production was achieved by an alkaliphilic strain Bacillus sp. WL-S20 using inexpensive peanut meal as nitrogen source and sodium hydroxide as neutralizing agent. In multi-pulse fed-batch fermentation of Bacillus sp. WL-S20, a l-lactic acid concentration of 225 g/l with a yield of 99.3% was obtained. In single-pulse fed-batch fermentation, a concentration of 180 g/l was obtained with a yield of 98.6%. No d-isomers of lactic acid were detected. The production of a high concentration of optically pure l-lactic acid by alkaliphilic Bacillus sp. WL-S20, combined with a low-cost nutrient and environment-friendly NaOH-based process, represent a potentially novel way for l-lactic acid production at an industrial scale.